Many firms give away small quantities of theirproductions as _______ so that people can try them before buying

Either you or I __ to blame for this.

They are developing new types of plants that can be grown in poor soil or even sand,and that areless to be attacked by pests and diseases. [ ]

What is your plan for the holiday, Paul—I’ll go on a trip to Yunnan Province with my family.— .

下列加框词活用现象不完全相同的一项（ ）